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Re: [2.25][ARM][GAS]Backport "Positively emit symbols for alignment."
- From: Tristan Gingold <gingold at adacore dot com>
- To: Renlin Li <renlin dot li at arm dot com>
- Cc: "binutils at sourceware dot org" <binutils at sourceware dot org>, "nickc at redhat dot com" <nickc at redhat dot com>, Marcus Shawcroft <Marcus dot Shawcroft at arm dot com>, Richard Earnshaw <Richard dot Earnshaw at arm dot com>
- Date: Tue, 16 Jun 2015 10:29:51 +0200
- Subject: Re: [2.25][ARM][GAS]Backport "Positively emit symbols for alignment."
- Authentication-results: sourceware.org; auth=none
- References: <553A3CAD dot 3050208 at arm dot com> <557FDD3E dot 4070401 at arm dot com>
> On 16 Jun 2015, at 10:24, Renlin Li <renlin.li@arm.com> wrote:
>
> Hi all,
>
> This is a merged backport patch from the following three. They together fix one problem, So I merge them into one backport patch. The description of problem is quoted below.
>
> The initial patch:
> https://sourceware.org/ml/binutils/2015-04/msg00381.html
>
> Fix two failing test case:
> https://sourceware.org/ml/binutils/2015-04/msg00457.html
>
> Fix a bug in the initial patch:
> https://sourceware.org/ml/binutils/2015-06/msg00045.html
>
>
> Binutils, ld, gas regression test Okay. Okay to commit?
Yes, ok for backporting.
>
> On 24/04/15 13:53, Renlin Li wrote:
>> Hi all,
>>
>> In arm_init_frag(), when ARM or THUMB are recorded, it will simply
>> return without doing anything. This is not correct in a few cases.
>>
>> For the following two cases:
>> case 1:
>> nop ----> MAP_ARM
>> .long 0 ---> MAP_DATA
>> .align 4 --->
>> ---->(1)
>> ----> start new frag
>> .word 0x12345678
>>
>> (1) paddings here are all treated as data, because the previous state is
>> MAP_DATA.
>>
>> case 2:
>> nop ----> MAP_ARM
>> .long 0 ---> MAP_DATA
>> .byte 1
>> .align 2 ---> (1)
>> ----> (2)
>> ----> start new frag
>> .long 0x12345678 ----> (3)
>>
>> stage 1: while parsing the input file:
>> (1) arm_init_frag early returns, No state change, no new symbol. (3)No
>> state change, no new symbol.
>> stage 2: Later, while writing the object file:
>> (2)MAP_DATA, MAP_ARM are inserted by insert_data_mapping_symol to handle
>> alignment. (3) interpreted as instruction because of the MAP_ARM
>> inserted at (2)
>>
>>
>> This change might generate redundant symbols, some of them can be
>> removed later. In check_mapping_symbols(), the symbols at the end of a
>> section, and overlapping symbols will be removed.
>>
>> gas checked without any new issues. Okay to commit?
> <arm-backport.diff>